FIG. 14 shows an example of a conventional power supply device. Electric power is supplied from a battery 51 that is installed in an engine room of an automobile to an electric junction box 53 via a cable 52, and is supplied from this electric junction box 53 to an electric junction box 55 that is installed in a vehicle interior via a wire harness 54. Ordinary, the wire harness 54 is a bundle of multiple power supply lines.
A plurality of wire harnesses 56 and 57 that extend from the electric junction box 55 are routed on a floor surface in the vehicle interior. The electric power is supplied, via the wire harnesses 56 and 57, to a plurality of electric devices 58 that are installed in a vehicle body.
The wire harness 54 penetrates a partition wall that separates the engine room from the vehicle interior, and is routed to the vehicle interior. A grommet that is made of rubber is fitted into the penetration portion formed in the partition wall to seal the vehicle interior against the engine room.
Furthermore, in the vehicle interior, the wire harnesses 56 and 57 are covered and protected by a protector, and are held on the floor surface by clamp members at predetermined intervals.
In recent years, due to an increase in the number of electric devices that are installed in an automobile, the number of electric wires that constitute a wire harness tends to increase, and the wire harness tends to grow in size. As a result, the partition wall between the engine room and the vehicle interior needs to be provided with a large through hole through which the wire harness passes.
Furthermore, due to the growing size of a wire harness, the space needed for routing the wire harness increases, the number of components needed for protecting and holding the wire harness increases, and the number of man-hours needed for the routing increases.
JP 3041397B discloses a connection structure in which an underbody of a vehicle body is provided with a thin circuit structure and a connector, in order to solve the problems regarding the growing size of a wire harness, and the number of man-hours needed for routing the wire harness.
However, because the number and the installation positions of electric devices vary depending on types of vehicles, the connection structure of JP 3041397B needs to prepare an underbody provided with a thin circuit structure and a connector that are specific for each type of vehicles. Accordingly, there is the problem that the automobile manufacturing cost increases.